// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/filters/vp9_raw_bits_reader.h"

#include <limits.h>

#include "base/logging.h"
#include "media/base/bit_reader.h"

namespace media {

Vp9RawBitsReader::Vp9RawBitsReader()
    : valid_(true)
{
}

Vp9RawBitsReader::~Vp9RawBitsReader() { }

void Vp9RawBitsReader::Initialize(const uint8_t* data, size_t size)
{
    DCHECK(data);
    reader_.reset(new BitReader(data, size));
    valid_ = true;
}

bool Vp9RawBitsReader::ReadBool()
{
    DCHECK(reader_);
    if (!valid_)
        return false;

    int value = 0;
    valid_ = reader_->ReadBits(1, &value);
    return valid_ ? value == 1 : false;
}

int Vp9RawBitsReader::ReadLiteral(int bits)
{
    DCHECK(reader_);
    if (!valid_)
        return 0;

    int value = 0;
    DCHECK_LT(static_cast<size_t>(bits), sizeof(value) * 8);
    valid_ = reader_->ReadBits(bits, &value);
    return valid_ ? value : 0;
}

int Vp9RawBitsReader::ReadSignedLiteral(int bits)
{
    int value = ReadLiteral(bits);
    return ReadBool() ? -value : value;
}

size_t Vp9RawBitsReader::GetBytesRead() const
{
    DCHECK(reader_);
    return (reader_->bits_read() + 7) / 8;
}

bool Vp9RawBitsReader::ConsumeTrailingBits()
{
    DCHECK(reader_);
    int bits_left = GetBytesRead() * 8 - reader_->bits_read();
    return ReadLiteral(bits_left) == 0;
}

} // namespace media
